Automatic crash detection

ABSTRACT

Systems and methods are disclosed for determining whether or not a crash involving a vehicle has occurred. The acceleration of the vehicle may be measured using, for example, an accelerometer of a mobile device, which may be located inside the vehicle. The system may determine the magnitude of each accelerometer measurement and whether the magnitude exceeds one or more acceleration magnitude thresholds. The system may also determine the number of accelerometer events within a time window and whether the number exceeds one or more count thresholds. The system may determine whether a crash involving the vehicle has occurred based on the magnitudes of acceleration, number of acceleration events, and various thresholds. In some examples, the system may confirm that a crash has occurred based on, for example, the location of the mobile device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of pending U.S. patent applicationSer. No. 15/880,187, filed Jan. 25, 2018 and entitled “Automatic CrashDetection,” which is a continuation of U.S. patent application Ser. No.15/665,710 (now U.S. Pat. No. 9,916,698), filed Aug. 1, 2017 andentitled “Automatic Crash Detection,” which is a continuation of U.S.patent application Ser. No. 14/685,067 (now U.S. Pat. No. 9,767,625),filed Apr. 13, 2015 and entitled “Automatic Crash Detection.” Each ofthe prior applications is incorporated herein by reference in itsentirety.

TECHNICAL FIELD

Aspects of the disclosure generally relate to the detection of vehiclecrashes using sensors and computing devices, which may be integratedinto mobile devices.

BACKGROUND

Typically, drivers of vehicles involved in crashes (or in some cases,emergency personnel) report crashes to insurance providers days or evenweeks after the crash. The delay in reporting crashes often results in adelay in processing insurance claims. The information that the drivergives to his or her insurance provider after the fact might also beincomplete or vague. For example, the driver might have forgotten thelocation of the accident.

SUMMARY

The following presents a simplified summary in order to provide a basicunderstanding of some aspects of the disclosure. The summary is not anextensive overview of the disclosure. It is neither intended to identifykey or critical elements of the disclosure nor to delineate the scope ofthe disclosure. The following summary merely presents some concepts ofthe disclosure in a simplified form as a prelude to the descriptionbelow.

Aspects of the disclosure relate to systems, methods, and computingdevices, such as a mobile computing device comprising an accelerometerconfigured to measure acceleration of at least one axis of theaccelerometer, a processor, and memory storing computer-executableinstructions that, when executed by the processor, cause the processorof the mobile computing device to receive acceleration events measuredby the accelerometer and determine whether a number of the accelerationevents measured by the accelerometer exceeds a threshold number ofacceleration events during a predetermined time window. If the number ofthe acceleration events measured by the accelerometer exceeds thethreshold number of acceleration events, a determination that the mobilecomputing device is within a vehicle and that the vehicle was involvedin a crash may be made. On the other hand, if the number of accelerationevents measured by the accelerometer does not exceed the thresholdnumber of acceleration events, a determination that the vehicle was notinvolved in a crash may be made.

The mobile computing device described herein may have memory storingadditional computer-executable instructions that, when executed by theprocessor of the mobile computing device, cause the process of themobile computing device to determine whether each of the accelerationevents exceeding the threshold number of acceleration events has amagnitude exceeding an acceleration magnitude threshold. Determiningthat the vehicle was involved in the crash may comprise determining thatthe vehicle was involved in the crash if the number of accelerationevents measured by the accelerometer exceeds the threshold number ofacceleration events, and each of the acceleration events exceeding thethreshold number of acceleration events has a magnitude exceeding theacceleration magnitude threshold.

In some aspects, the acceleration events may comprise accelerationevents having a magnitude exceeding an acceleration magnitude threshold.The accelerometer may comprise three axes, and the magnitude maycomprise at least one of a sum of the absolute values of each of thethree axes of the accelerometer, a sum of the squares of each of thethree axes of the accelerometer, and a magnitude of a single axis of theaccelerometer. Additionally or alternatively, the acceleration magnitudethreshold may comprise a plurality of acceleration magnitude thresholds,and the memory of the mobile computing device may store additionalcomputer-executable instructions that, when executed by the processor,cause the processor of the mobile computing device to determine aseverity of the crash based on whether one or more of the plurality ofacceleration magnitude thresholds has been exceeded and responsive todetermining that the vehicle was involved in the crash.

The time window disclosed herein may comprise a number of accelerationsamples measured periodically by the accelerometer. Additionally oralternatively, the time window may comprise a time value greater than 5milliseconds.

In some aspects, the mobile computing device may further comprisecommunication circuitry configured to wirelessly communicate with otherdevices. The memory of the mobile computing device may store additionalcomputer-executable instructions that, when executed by the processor,cause the processor of the mobile computing device to send, via thecommunication circuitry and to a crash detection server, a messagecomprising information identifying an owner of the mobile computingdevice, information identifying the mobile computing device, andinformation identifying a location of the mobile computing device. Themessage may be sent responsive to a determination that the vehicle wasinvolved in the crash. The mobile computing device may comprise a mobilephone, and the memory of the mobile phone may store additionalcomputer-executable instructions that, when executed by the processor,cause the processor of the mobile phone to receive, via thecommunication circuitry, a phone call. The phone call my be receivedresponsive to the message being sent to the crash detection server.

Aspects of the disclosure relate to systems and methods for identifying,by a mobile computing device, a time window, an acceleration magnitudethreshold, and a number of acceleration events threshold. The system andmethod may include a determination of a number of acceleration eventsmeasured by an accelerometer of the mobile computing device exceedingthe acceleration magnitude threshold during the time window. The systemand method may also include a determination that a the mobile computingdevice is within a vehicle and that the vehicle was involved in a crashresponsive to determining that the number of acceleration eventsmeasured by the accelerometer of the mobile computing device exceedingthe acceleration magnitude threshold also exceeds the number ofacceleration events threshold.

The systems and methods disclosed herein may include a determination ofa location of the mobile computing device and a confirmation that thecrash occurred based on the location of the mobile computing device.Moreover, the mobile computing device may identify a second accelerationmagnitude threshold greater than the acceleration magnitude threshold. Adetermination of a second number of acceleration events measured by theaccelerometer of the mobile computing device exceeding both theacceleration magnitude threshold and the second acceleration magnitudethreshold may be made. The severity of the crash may be determined basedon the number of acceleration events exceeding the accelerationmagnitude threshold and the second number of acceleration eventsexceeding both the acceleration magnitude threshold and the secondacceleration magnitude threshold.

Other features and advantages of the disclosure will be apparent fromthe additional description provided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention and theadvantages thereof may be acquired by referring to the followingdescription in consideration of the accompanying drawings, in which likereference numbers indicate like features, and wherein:

FIG. 1 illustrates a network environment and computing systems that maybe used to implement aspects of the disclosure.

FIG. 2 is a diagram illustrating various example components of a crashdetection system according to one or more aspects of the disclosure.

FIG. 3 is a flow diagram illustrating an example method of initializinga crash detection system according to one or more aspects of thedisclosure.

FIG. 4 is a flow diagram illustrating an example method of detecting acrash according to one or more aspects of the disclosure.

DETAILED DESCRIPTION

In the following description of the various embodiments, reference ismade to the accompanying drawings, which form a part hereof, and inwhich is shown by way of illustration, various embodiments of thedisclosure that may be practiced. It is to be understood that otherembodiments may be utilized.

As will be appreciated by one of skill in the art upon reading thefollowing disclosure, various aspects described herein may be embodiedas a method, a computer system, or a computer program product.Accordingly, those aspects may take the form of an entirely hardwareembodiment, an entirely software embodiment or an embodiment combiningsoftware and hardware aspects. In addition, aspects may take the form ofa computing device configured to perform specified actions. Furthermore,such aspects may take the form of a computer program product stored byone or more computer-readable storage media having computer-readableprogram code, or instructions, embodied in or on the storage media. Anysuitable computer readable storage media may be utilized, including harddisks, CD-ROMs, optical storage devices, magnetic storage devices,and/or any combination thereof. In addition, various signalsrepresenting data or events as described herein may be transferredbetween a source and a destination in the form of electromagnetic wavestraveling through signal-conducting media such as metal wires, opticalfibers, and/or wireless transmission media (e.g., air and/or space).

FIG. 1 illustrates a block diagram of a computing device 101 in a crashdetection system 100 that may be used according to one or moreillustrative embodiments of the disclosure. The crash detectioncomputing device 101 may have a processor 103 for controlling overalloperation of the computing device 101 and its associated components,including RAM 105, ROM 107, input/output module 109, and memory unit115. The computing device 101, along with one or more additional devices(e.g., terminals 141, 151) may correspond to any of multiple systems ordevices, such as crash detection computing devices or systems,configured as described herein for transmitting and receiving sensordata, detecting a crash, and confirming that the crash (rather than anon-crash event) occurred. Sensor data can include data collected frommobile devices (e.g., the driver's mobile phone), vehicle sensors,and/or on-board diagnostic (OBD) systems.

Input/Output (I/O) module 109 may include a microphone, keypad, touchscreen, and/or stylus through which a user of the computing device 101may provide input, and may also include one or more of a speaker forproviding audio input/output and a video display device for providingtextual, audiovisual and/or graphical output. Software may be storedwithin memory unit 115 and/or other storage to provide instructions toprocessor 103 for enabling device 101 to perform various functions. Forexample, memory unit 115 may store software used by the device 101, suchas an operating system 117, application programs 119, and an associatedinternal database 121. The memory unit 115 includes one or more ofvolatile and/or non-volatile computer memory to storecomputer-executable instructions, data, and/or other information.Processor 103 and its associated components may allow the crashdetection computing device 101 to execute a series of computer-readableinstructions to transmit or receive sensor data, process sensor data,and determine or confirm crash and non-crash events from the sensordata.

The crash detection computing device 101 may operate in a networkedenvironment 100 supporting connections to one or more remote computers,such as terminals/devices 141 and 151. Crash detection computing device101, and related terminals/devices 141 and 151, may include devicesinstalled in vehicles, mobile devices that may travel within vehicles,or devices outside of vehicles that are configured to receive andprocess vehicle and other sensor data. Thus, the crash detectioncomputing device 101 and terminals/devices 141 and 151 may each includepersonal computers (e.g., laptop, desktop, or tablet computers), servers(e.g., web servers, database servers), vehicle-based devices (e.g.,on-board vehicle computers, short-range vehicle communication systems,sensor and telematics devices), or mobile communication devices (e.g.,mobile phones, portable computing devices, and the like), and mayinclude some or all of the elements described above with respect to thecrash detection computing device 101. The network connections depictedin FIG. 1 include a local area network (LAN) 125 and a wide area network(WAN) 129, and a wireless telecommunications network 133, but may alsoinclude other networks. When used in a LAN networking environment, thecrash detection computing device 101 may be connected to the LAN 125through a network interface or adapter 123. When used in a WANnetworking environment, the device 101 may include a modem 127 or othermeans for establishing communications over the WAN 129, such as network131 (e.g., the Internet). When used in a wireless telecommunicationsnetwork 133, the device 101 may include one or more transceivers,digital signal processors, and additional circuitry and software forcommunicating with wireless computing devices 141 (e.g., mobile phones,short-range vehicle communication systems, vehicle sensing andtelematics devices) via one or more network devices 135 (e.g., basetransceiver stations) in the wireless network 133.

It will be appreciated that the network connections shown areillustrative and other means of establishing a communications linkbetween the computers may be used. The existence of any of variousnetwork protocols such as TCP/IP, Ethernet, FTP, HTTP and the like, andof various wireless communication technologies such as GSM, CDMA, Wi-Fi,and WiMAX, is presumed, and the various computing devices and crashdetection system components described herein may be configured tocommunicate using any of these network protocols or technologies.

Additionally, one or more application programs 119 used by the crashdetection computing device 101 may include computer executableinstructions (e.g., sensor data analysis programs, crash detectionalgorithms, and the like) for transmitting and receiving sensor andcrash data and performing other related functions as described herein.

Sensor data may refer to information pertaining to one or more actionsor events performed by a vehicle and can include aspects of informationidentified or determined from data collected from a vehicle or mobiledevice. Sensor data can include, for example, location data, speed orvelocity data, acceleration data, presence data, time data, directiondata, mobile device orientation data, rotation/gyroscopic data, and thelike.

FIG. 2 is a diagram illustrating various example components of a crashdetection system 200 according to one or more aspects of the disclosure.The crash detection system 200 may include a vehicle 210, other vehicles(not illustrated), a location detection system 220, a crash detectionserver 250, and additional related components. Each component shown inFIG. 2 may be implemented in hardware, software, or a combination of thetwo. Additionally, each component of the crash detection system 200 mayinclude a computing device (or system) having some or all of thestructural components described above for computing device 101.

Vehicle 210 may be, for example, an automobile, motorcycle, scooter,bus, recreational vehicle, boat, or other vehicle for which sensor orcrash data may be collected and analyzed. A mobile computing device 216within the vehicle 210 may be used to collect sensor or crash data(e.g., via sensors 218) and/or to receive sensor or crash data from thevehicle 210 (e.g., via vehicle sensors 219). The mobile device 216 mayprocess the data to detect a crash or non-crash event and/or transmitthe sensor or crash data to the crash detection server 250 or otherexternal computing devices. Mobile computing device 216 may be, forexample, mobile phones, personal digital assistants (PDAs), tabletcomputers, laptop computers, smartwatches, and other devices that may becarried by drivers or passengers inside or outside of the vehicle 210.The mobile computing device 216 may contain some or all of thehardware/software components as the computing device 101 depicted inFIG. 1. Software applications executing on the mobile device 216 may beconfigured to receive sensor data from sensors 218, such asacceleration, velocity, location, and the like and/or communicate withvehicle sensors 219 or other vehicle communication systems to sense orreceive driving data. For example, mobile device 216 equipped withGlobal Positioning System (GPS) functionality may determine vehiclelocation, speed, direction and other basic driving data without needingto communicate with vehicle sensors or external vehicle systems. Inother examples, software on the mobile device 216 may be configured toreceive some or all of the sensed data collected by sensors 219 of thevehicle 210.

When mobile computing device 216 within the vehicle 210 is used to sensevehicle data, the mobile computing device 216 may store, analyze, and/ortransmit the vehicle data to one or more other computing devices. Forexample, mobile device 216 may transmit vehicle data directly to crashdetection server 250, and thus may be used instead of sensors orcommunication systems of the vehicle 210.

The mobile device 216 may include various sensors 218 capable ofdetecting and recording conditions at and operational parameters of thevehicle 210 if the mobile device 216 is inside the vehicle. The sensors218 may be used to sense, for example, the location of the mobile device216, such as the GPS coordinates (e.g., latitude and longitude). Thelocation of the mobile device 216 may also be determined based onwireless networks the mobile device has connected to, such as Wi-Finetworks, cellular networks, and the like. Images taken by a camera ofthe mobile device 216 may also be used to determine the location. Forexample, the mobile device may capture an image before, during, or afterthe accidents, and the captured image may be compared to images storedin one or more databases (e.g., databases of a search engine). Once amatch is found, the location of the mobile device 216 may be determinedbased on the tagged location of the matching image in the database. Insome aspects, location may be detected, for example, at least once persecond (e.g., 60 Hz).

The sensors 218 of the mobile device 216, such as a GPS and/or acompass, may sense the speed and/or direction at which the mobile device216 (and accordingly vehicle 210) is traveling. An accelerometer of themobile device 216 may sense the acceleration of the mobile device. Agyroscope may be used to determine the orientation of the mobile device.In some aspects, orientation may be detected, for example, at a rate of90 Hz. The gyroscope may also be used to measure the speed of rotationof the mobile device 216. A magnetometer may be used to measure thestrength and direction of the magnetic field relative to the mobiledevice. The sensors 218 previously described are exemplary, and themobile device 216 may include any other sensors used for crashdetection.

The data collected by the mobile device 216 may be stored and/oranalyzed within the mobile device 216. The processing components of themobile computing device 216 may be used to analyze sensor data,determine that a crash has or has not occurred, and confirm whether ornot the crash has occurred. Additionally or alternatively, the mobiledevice 216 may transmit, via a wired or wireless transmission network,the data to one or more external devices for storage or analysis, suchas vehicle computer 214 or crash detection server 250. In other words,mobile computing device 216 may be used in conjunction with, or in placeof, the vehicle computer 214 or crash detection server 250 to detectcrashes.

The vehicle computer 214 of the vehicle 210 may contain some or all ofthe hardware/software components as the computing device 101 depicted inFIG. 1. The vehicle computer 214 may receive sensor or crash data fromthe mobile device 216 and/or from sensors 219 built into the vehicle210. For example, vehicle computer 214 may receive accelerometer datafrom the mobile device 216 or an accelerometer in the vehicle 210 anduse the accelerometer data to determine whether or not a crash hasoccurred. Additionally or alternatively, the vehicle computer 214 mayact as a gateway device between the mobile device 216 and the crashdetection server 250. For example, the vehicle computer 214 may receivesensor data (or data indicating that a crash has occurred) from themobile device 216 and forward the received data to the crash detectionserver 250. The vehicle 210 may include a short-range communicationsystem 212, which will be described in further detail below.

The system 200 may include a crash detection server 250, containing someor all of the hardware/software components as the computing device 101depicted in FIG. 1. The crash detection server 250 may include hardware,software, and network components to receive data from one or morevehicles 210 (e.g., via vehicle computer 214), mobile device 216, andother data sources. The crash detection server 250 may include a drivingand driver data database 252 and crash detection computer 251 torespectively store and analyze data received from vehicles, mobiledevices, and other data sources. The crash detection server 250 mayinitiate communication with and/or retrieve data from vehicle 210wirelessly via vehicle computer 214, mobile device 216, or by way ofseparate computing systems over one or more computer networks (e.g., theInternet). Additionally, the crash detection server 250 may receiveadditional data from other non-vehicle or mobile device data sources,such as external databases containing driver information (e.g., thedriver's name, license number, home or work address, and the like) andvehicle information (e.g., Vehicle Identification Number (VIN), licenseplate number, vehicle make and model, and the like).

The crash detection computer 251 may be configured to retrieve data fromthe database 252, or may receive driving data directly from vehicle 210,mobile device 216, or other data sources. The crash detection computer251 may perform crash detection analyses and other related functions, aswill be described in further detail in the examples below. The analysesdescribed herein may be performed entirely in the crash detectioncomputer 251 of the crash detection server 250, entirely in the vehiclecomputer 214, or entirely in the mobile device 216. In other examples,certain analyses may be performed by vehicle computer 214, otheranalyses may be performed by the crash detection computer 251, and yetother analyses may be performed by the mobile device 216.

The system 200 may also include an external location detection device220, containing some or all of the hardware/software components as thecomputing device 101 depicted in FIG. 1. The location detection device220 may be used to determine the location of the mobile device 216and/or vehicle 210. The location detection device 220 may include one ormore location sensors 222, transceivers 224 for transmitting andreceiving data, and a location detection computer 226 used to processdata and determine the location of the mobile device 216 and/or vehicle210. In some aspects, the location of the mobile device 216 may bedetermined using GPS, and the location detection device 220 may compriseone or more GPS satellites. Location may also be determined using one ormore Wi-Fi network, and the location detection device 220 may compriseone or more Wi-Fi access points. Location may also be determined usingone or more cellular network, and the location detection device 220 maycomprise one or more cellular network towers. Location may also bedetermined using captured images, and the location detection device 220may comprise an on-road camera.

In some aspects, the location of the mobile device 216 and/or vehicle210 may be determined using another mobile device and/or vehicle. Forexample, vehicle 210 may be configured to perform vehicle-to-vehicle(V2V) communications, by establishing connections andtransmitting/receiving vehicle data to and from other nearby vehiclesusing short-range communication system 212.

Short-range communication system 212 is a vehicle-based datatransmission system configured to transmit vehicle data to other nearbyvehicles, and to receive vehicle data from other nearby vehicles. Insome examples, communication system 212 may use the dedicatedshort-range communications (DSRC) protocols and standards to performwireless communications between vehicles. In the United States, 75 MHzin the 5.850-5.925 GHz band have been allocated for DSRC systems andapplications, and various other DSRC allocations have been defined inother countries and jurisdictions. However, the short-rangecommunication system 212 need not use DSRC, and may be implemented usingother short-range wireless protocols in other examples, such as WLANcommunication protocols (e.g., IEEE 802.11), Bluetooth (e.g., IEEE802.15.1), or one or more of the Communication Access for Land Mobiles(CALM) wireless communication protocols and air interfaces.

The V2V transmissions between the short-range communication system 212and another vehicle's communication system may be sent via DSRC,Bluetooth, satellite, GSM infrared, IEEE 802.11, WiMAX, RFID, and/or anysuitable wireless communication media, standards, and protocols. Incertain systems, the short-range communication system 212 may includespecialized hardware installed in vehicle 210 (e.g., transceivers,antennas, etc.), while in other examples the communication system 212may be implemented using existing vehicle hardware components (e.g.,radio and satellite equipment, navigation computers) or may beimplemented by software running on the mobile device 216 of drivers andpassengers within the vehicle 210.

The range of V2V communications between vehicle communication systemsmay depend on the wireless communication standards and protocols used,the transmission/reception hardware (e.g., transceivers, power sources,antennas), and other factors. Short-range V2V communications may rangefrom just a few feet to many miles. V2V communications also may includevehicle-to-infrastructure (V2I) communications, such as transmissionsfrom vehicles to non-vehicle receiving devices, for example, tollbooths, rail road crossings, and road-side traffic monitoring devices.Certain V2V communication systems may periodically broadcast data from avehicle 210 to any other vehicle, or other infrastructure device capableof receiving the communication, within the range of the vehicle'stransmission capabilities. For example, a vehicle 210 may periodicallybroadcast (e.g., every 0.1 second, every 0.5 seconds, every second,every 5 seconds, etc.) certain vehicle data via its short-rangecommunication system 212, regardless of whether or not any othervehicles or reception devices are in range. In other examples, a vehiclecommunication system 212 may first detect nearby vehicles and receivingdevices, and may initialize communication with each by performing ahandshaking transaction before beginning to transmit its vehicle data tothe other vehicles and/or devices.

The types of vehicle data transmitted by the vehicle 210 may depend onthe protocols and standards used for the V2V communication, the range ofcommunications, whether a crash has been detected, and other factors. Incertain examples, the vehicle 210 may periodically broadcastcorresponding sets of similar vehicle driving data, such as the location(which may include an absolute location in GPS coordinates or othercoordinate systems, and/or a relative location with respect to anothervehicle or a fixed point), speed, and direction of travel. In certainexamples, the nodes in a V2V communication system (e.g., vehicles andother reception devices) may use internal clocks with synchronized timesignals, and may send transmission times within V2V communications, sothat the receiver may calculate its distance from the transmitting nodebased on the difference between the transmission time and the receptiontime. The state or usage of the vehicle's 210 controls and instrumentsmay also be transmitted, for example, whether the vehicle isaccelerating, braking, turning, and by how much, and/or which of thevehicle's instruments are currently activated by the driver (e.g., headlights, turn signals, hazard lights, cruise control, 4-wheel drive,traction control, windshield wipers, etc.). Vehicle warnings such asdetection by the vehicle's 210 internal systems that the vehicle isskidding, that an impact has occurred, or that the vehicle's airbagshave been deployed, also may be transmitted in V2V communications.

The mobile computing device 216 may be used instead of, or inconjunction with, short-range communication system 212. For example, themobile device 216 may communicate directly with the other vehicle ordirectly with another mobile device, which may be inside or outside ofthe other vehicle. Additionally or alternatively, the other vehicle maycommunicate location information to vehicle 210, and vehicle 210 may inturn communicate this location information to the mobile device 216. Anydata collected by any vehicle sensor or mobile device 216 sensor may betransmitted via V2V or other communication to other nearby vehicles,mobile devices, or infrastructure devices receiving V2V communicationsfrom communication system 212 or communications directly from mobiledevice 216. Further, additional vehicle driving data not from thevehicle's sensors (e.g., vehicle make/model/year information, driverinformation, etc.) may be collected from other data sources, such as adriver's or passenger's mobile device 216, crash detection server 250,and/or another external computer system, and transmitted using V2Vcommunications to nearby vehicles and other transmitting and receivingdevices using communication system 212.

Systems and methods described herein may detect vehicle crashes (e.g.,accidents) based on the number of high magnitude accelerometer readingswithin a particular time window. For example, a computing device 101 mayreceive five samples of accelerometer readings made within a timewindow. The computing device 101 may determine that a crash has occurredif the magnitude of three or more of the accelerometer readings isgreater than a threshold. Otherwise, the computing device 101 maydetermine that a non-crash event occurred, such as the mobile device 216being dropped or a hard braking event of the vehicle 210. The previousdescription is merely exemplary, and additional examples of the crashdetection system 200 and method performed by the system are describedbelow.

FIG. 3 is a flow diagram illustrating an example method of initializinga crash detection system according to one or more aspects of thedisclosure. As will be described below, various parameters, such as theacceleration magnitude threshold, the time window, and/or the number ofacceleration events threshold may be updated in order to improve theaccuracy of the crash detection algorithm described herein. The updatesmay be based on an analysis of crash and non-crash data collected from aplurality of mobile devices and/or from a plurality of vehicles and usedto improve the crash detection algorithm (e.g., to yield better resultsthrough data analysis). The example of FIG. 3 may be performed by one ormore computing devices in a crash detection system 200, such as vehiclecomputer 214, a crash detection computer 251, a mobile computing device216, and/or other computer systems.

In step 305, a computing device, such as the crash detection server 250or mobile device 216, may determine whether to update an accelerationmagnitude threshold. The acceleration magnitude threshold may be usedalone or in combination with the number of high acceleration eventswithin a time window to determine whether a crash has occurred. As willbe described in further detail in the examples below, a computing devicemay use the acceleration magnitude threshold to distinguish between acrash event (e.g., magnitude of acceleration exceeding the threshold)and a hard braking event (e.g., magnitude of acceleration not exceedingthe threshold).

The magnitude and direction of acceleration may be measured by, forexample, an accelerometer of the mobile device 216 and/or vehicle 210.The accelerometer may include three different axes (i.e., x-axis,y-axis, and z-axis), and acceleration measurements may be taken for eachaxis. The magnitude of acceleration for the purposes of crash detectionmay be determined using any number of methods. For example, themagnitude of acceleration may be determined based on the sum of theabsolute values of all three axes of the accelerometer, as illustratedin the following algorithm:|x|+|y|+|z|

The computing device may add an offset to the axis corresponding to thedirection of gravity in order to account for the effect of gravity onacceleration measurements. For example, if the direction of gravitycorresponds to the z axis, and acceleration is measured using thestandard gravity unit of measurement (G or 9.8 m/s²), the followingalgorithm may be used to determine the magnitude of acceleration for thepurposes of crash detection:|x|+|y|+|z+1|

Alternatively, if the orientation of the mobile device 216 is unknown, ahigh-pass filter may be used to remove the effect of gravity. Themagnitude of acceleration may alternatively be determined based on thesum of the squares of all three axes of the accelerometer, asillustrated in the following algorithm:x²+y²+z²

The computing device may add an offset to the axis corresponding to thedirection of gravity, such as the z-axis, as illustrated in thefollowing algorithm:x²+y²+(z+1)²

In some aspects, the magnitude of acceleration may be determined usingthe magnitude of a single axis of the accelerometer. If a single axis isused, the computing device may choose the axis to measure based on theorientation of the mobile device 216. For example, the gyroscope andcompass of the mobile device 216 may be used to determine theorientation of mobile device, such as by determining the direction ofthe force of gravity. The orientation of the mobile device may be fixedby a cradle attached to the vehicle 210 (e.g., the windshield ordashboard of the vehicle 210) configured to hold the mobile device. Themobile device 216 and/or vehicle 210 may detect whether the mobiledevice 216 is in the cradle using, for example, wired connections (e.g.,if the mobile device 216 is plugged into the cradle), wirelessconnections (e.g., near-field communication (NFC), wireless charging,etc.), or presence sensors (e.g., light sensors on the mobile device 216or cradle, which may be covered when the mobile device 216 is placed inthe cradle). If the mobile device 216 is fixed by the cradle, thecomputing device may select the appropriate axis (or axes) to measurefor acceleration, such as the x-axis, the y-axis, the z-axis, or acombination thereof. Each axis may use a different accelerationmagnitude threshold for the purposes of determining a crash or non-crashevent.

Returning to FIG. 3, in step 310, the computing device may determine anew acceleration magnitude threshold if the computing device determinedin step 305 to update the threshold. The threshold may be updated inorder to improve the accuracy of the crash detection algorithm, based onan analysis of crash and non-crash data collected from a plurality ofmobile devices and/or from a plurality of vehicles. The threshold mayalso be updated based on the size of the vehicle 210. For example, aheavier vehicle (e.g., having a weight greater than a threshold, such as4000 lbs.) may use a higher threshold to trigger a detection of a crashbecause heavier vehicles have more inertia and may experience largerforce during a crash. A lighter vehicle (e.g., having a weight less thana threshold, such as 4000 lbs.) may use a lower threshold to trigger adetection of a crash because lighter vehicles have less inertia thanheavier vehicles.

Exemplary, non-limiting acceleration magnitude thresholds include 3G,4G, and 8G. In some aspects, the computing device may use multipleacceleration magnitude thresholds to determine the severity of thecrash. For example, the computing device may be configured for threethresholds: 3G, 8G, and 60G. If the magnitude of acceleration is below3G, the computing device may determine that a crash did not occur. Ifthe magnitude of acceleration is between 3G and 8G, the computing devicemay determine that a minor crash occurred. If the magnitude ofacceleration is between 8G and 60G, the computing device may determinethat a moderate crash occurred. If the magnitude of acceleration isabove 60G, the computing device may determine that a severe crashoccurred. While the above example uses three thresholds, any number ofthresholds (and thus levels of severity) may be used.

In some aspects, the threshold selected may depend on the configurationand capabilities of the accelerometer in the mobile device 216 orvehicle 210. For example, if the accelerometer is capable of measuringaccelerations of up to +/−16G, the computing device may select anythreshold value(s) less than 16G.

In step 315, the computing device may determine whether to update a timewindow. The time window may establish a period of time for which thecomputing device makes acceleration measurements for the purposes ofdetermining a crash. The time window may be represented as a time value,such as 5 milliseconds. Alternatively, the time window may berepresented as a number of acceleration measurements, such as 7measurements, if the accelerometer makes periodic measurements (e.g.,125 measurements per second or 125 Hz). In the latter example, the timevalue for the time window may be 5.6 milliseconds (i.e., 7measurements÷125 measurements/second). 125 Hz is merely exemplary, andother non-limiting examples include 90 Hz and 100 Hz.

Other exemplary, non-limiting examples of the number of accelerationmeasurements include 3, 5, and 10 measurements. As will be described infurther detail in the examples below, a computing device may determinewhether the number of high magnitude acceleration measurements withinthe time window exceed a threshold number of acceleration measurements.In step 320, the computing device may determine a new time window if thecomputing device determined in step 315 to update the window. The timewindow may be updated in order to improve the accuracy of the crashdetection algorithm, based on an analysis of crash and non-crash datacollected from a plurality of mobile devices and/or from a plurality ofvehicles. The time window may be increased to screen out noise or toobserve multiple collisions that occur during a crash.

In step 325, the computing device may determine whether to update athreshold number of acceleration events. In step 330, the computingdevice may determine a new threshold number of acceleration events ifthe computing device determines to update the threshold in step 325. Thethreshold number of acceleration events may be used in combination withthe acceleration magnitude threshold and time window previouslydescribed to determine whether a crash has occurred. For example, if thenumber of high magnitude acceleration events during the time windowexceeds the threshold number of acceleration events, the computingdevice may determine that a crash occurred. Otherwise, the computingdevice may determine that a non-crash event occurred, such as the mobiledevice being dropped. In some aspects, the time window described abovemay be chosen to be long enough to distinguish the short duration of adropped phone's impact with a surface from the longer duration of avehicle crash. For example, the period of time may be greater than orequal to 5 milliseconds.

As previously described, each of the acceleration magnitude threshold,the time window, and/or the number of acceleration events threshold maybe updated according to the steps illustrated in FIG. 3. The updatedvalues may be sent as an update to an application on the mobile device216 (e.g., in the case of a mobile deployment) or as a firmware update(e.g., in the case of a device deployment).

A brief, non-limiting example of a computing device using theacceleration magnitude threshold, time window, and number ofacceleration events threshold will now be described. Assume that theacceleration magnitude threshold is 4G, time window is 5 measurements(or 4 milliseconds measured periodically at 125 Hz), and the number ofacceleration events threshold is 3 measurements. The computing devicemay receive 5 acceleration measurements from the accelerometer duringthe time window and determine the magnitude of acceleration for each ofthe 5 measurements. If the magnitude of acceleration for at least 3 ofthe measurements exceeds 4G, the computing device may determine that acrash occurred. Otherwise, the computing device may determine that anon-crash event occurred, such as the phone being dropped or a hardbraking event. Additional examples of crash detection will now beprovided with reference to FIG. 4.

FIG. 4 is a flow diagram illustrating an example method of detecting acrash according to one or more aspects of the disclosure. The example ofFIG. 4 may be performed by one or more computing devices in a crashdetection system 200, such as vehicle computer 214, a crash detectioncomputer 251, a mobile computing device 216, and/or other computersystems.

In step 405, a computing device may determine whether a trigger eventhas occurred. The trigger event may indicate the possibility of a crash,such as a magnitude of acceleration that exceeds an accelerationmagnitude threshold. In some aspects, a threshold smaller than theacceleration magnitude threshold may be used to trigger the computingdevice to initiate detection of a crash. The trigger event may also bebased on GPS measurements. For example, the computing device maydetermine that a trigger event has occurred if the change in speedmeasured by the GPS system of the mobile device 216 (or vehicle 210) isgreater than a certain threshold. The computing device may wait for atrigger event before proceeding to step 410.

In step 410, the computing device may start the time window for takingacceleration measurements. As previously explained, the time window maycomprise a time period and/or a number of measurements to take (e.g., ifthe acceleration measurements are periodically taken, such as everymillisecond). The computing device may also initialize the time windowto t=0 (the base time). In step 415, the computing device may initializean acceleration count, which may be used to track the number of highacceleration events detected during the time window. The accelerationcount may be initialized to 0 if the event that triggered the start ofthe time window is not included in the acceleration count, such as ifthe magnitude of the acceleration event trigger did not exceed theacceleration magnitude threshold or if the event is not otherwise to becounted. On the other hand, the acceleration count may be initialized to1 if the magnitude of the acceleration event trigger exceeded theacceleration magnitude threshold or if the event is otherwise to becounted.

Instead of waiting for a trigger event (step 405) to trigger the timewindow (step 410) and to initialize the acceleration count (step 415),the computing device may use a rolling time window. Sensor data, such asacceleration data and/or GPS data, may be periodically made by andstored in, for example, the mobile device 216's memory. When a newsensor reading is made, the computing device may drop the oldest readingin the time window and add the new reading to the window.

In step 420, the computing device may determine whether the time windowhas ended. For example, if the time window is 5 milliseconds, thecomputing device may determine that the time window has ended when t=5ms. If the time window is 5 measurements, the computing device maydetermine that the time window has ended when 5 measurements have beentaken since the beginning of the time window.

If the time window has not ended (step 420: N), in step 425, thecomputing device may determine whether the magnitude of the accelerationfor the currently sampled acceleration exceeds the accelerationmagnitude threshold. For example, if the threshold is 4G and themagnitude of the current acceleration sample is 2.5G (step 425: N), thecomputing device may return to step 420 to determine whether the timewindow has ended and/or to take the next measurement. On the other hand,if the magnitude of the current acceleration sample is 4.6G (step 425:Y), the computing device may proceed to step 428.

In step 428, the computing device may optionally determine whether theprevious acceleration sample (e.g., immediately previous accelerationsample) also exceeded the acceleration magnitude threshold. If theprevious sample did not exceed the threshold (step 428: N), thecomputing device may proceed to step 430 and increment the accelerationcount. On the other hand, if the previous sample exceeded the threshold(step 428: Y), the computing device might not increment the accelerationcount and instead return to step 420. In other words, the computingdevice may optionally determine whether a crash has occurred based onthe number of non-consecutive acceleration readings above theacceleration magnitude threshold. The computing device might not rely onconsecutive acceleration samples. In other words, and as will bedescribed below, the computing device may determine that a crashoccurred based on either consecutive acceleration samples ornon-consecutive acceleration samples.

In step 435, the computing device may determine whether the accelerationcount within the time window has exceeded the number of accelerationevents threshold. For example, if the threshold is two high magnitudeacceleration events and the acceleration count is two (step 435: N), thecomputing device may return to step 420 to determine whether the timewindow has ended and/or to take the next measurement. On the other hand,if the acceleration count is three (step 435: Y), the computing devicemay proceed to step 445 and determine that a crash has occurred. Thecomputing device may also determine that the mobile device is locatedwithin the vehicle involved in the crash. As previously explained, thecomputing device may determine the severity of the crash based on aplurality of acceleration magnitude thresholds. For example, if one,some, or all of the measured magnitudes exceeds a high threshold, thecomputing device may determine that a severe crash occurred. If one,some, or all of the magnitudes falls between a medium and highthreshold, the computing device may determine that a moderate crashoccurred. If one, some, or all of the magnitudes falls between a low andmedium threshold, the computing device may determine that a minor crashoccurred. If the mobile device 216 or vehicle computer 214 determinesthat a crash occurred in step 445, the device may generate a messageindicating the crash and send the message to, for example, crashdetection server 250.

In step 450, the computing device may confirm whether a crash occurredby analyzing additional data. In some aspects, the computing device mayconfirm the accident based on GPS readings. For example, the computingdevice may confirm the accident based on the change in speed of thevehicle 210 being greater than a threshold (e.g., indicating a hard stopor deceleration) and the GPS coordinates of the vehicle after the hardstop or deceleration falling within a certain radius of the location ofthe hard stop or deceleration for a particular length of time (e.g.,thirty seconds).

A JavaScript Object Notation (JSON) algorithm may be used for crashdetermination and confirmation, as previously described. An exemplaryJSON structure may be as follows:

-   -   {        -   “gps”:{            -   “deceleration”:0.33,            -   “stop_def_radius”:50,            -   “stop_wait_time:30        -   },        -   “accelerometer”:{            -   “window_length”:7,            -   “breach_threshold”:5,            -   “num_breaches”:3        -   }    -   }

A JSON dictionary may include keys for “gps” and “accelerometer.” Thefollowing table illustrates the keys for “accelerometer”:

Key Definition window_length Number of x, y, and z acceleration readingsconsidered (time window) breach_threshold Threshold for determining whenthe acceleration is considered high. Units may be G = 9.81 m/s²num_breaches Number of acceleration readings within the window for whichthe magnitude of acceleration exceeds the breach_threshold for a crash

The following table illustrates the keys for “gps”:

Key Definition deceleration Threshold the difference in speed should bebelow. Units may be G = 9.81 m/s² stop_def_radius Radius a number of GPSreadings after the hard deceleration should lie within. Units may bemeters stop_wait_time Number of readings after the hard decelerationthat should fall within the stop_def_radius. Units may be seconds

The above JSON configuration example may be used to determine andconfirm a crash in the following scenario. The GPS trail may show amagnitude of deceleration of 0.33G followed by the vehicle not movingmore than 50 m in 30 s. Within an acceleration window of length 7 (e.g.,a time value of 7/90 seconds for 90 Hz sampling) starting at the sametime as the above GPS deceleration event, at least 3 of the 7acceleration magnitude readings exceeds 5G.

Additionally or alternatively, the computing device may confirm (afterdetecting) the crash based on the location of the mobile device 216and/or vehicle 210. For example, if the computing device determines thatthe mobile device 216 is on a road (or within a predetermined radiusfrom a road), the computing device may confirm the crash. Otherwise, thecomputing device may determine that a crash did not occur. The locationof the mobile device 216 and/or vehicle 210 may be determined using thelocation detection device 220, as previously described. The computingdevice may determine the existence of a road by accessing a database ofmaps, such as GPS or search engine maps. If the crash is not confirmed(step 450: N), the computing device may return to step 405 to determinewhether another trigger event has occurred. If the crash is confirmed(step 450: Y), the computing device may proceed to step 455.

In step 455, the computing device may generate and/or store the crashdata, such as the number of acceleration events counted, the severity ofthe crash, and the threshold values. The computing device may alsogenerate and/or store the location of the crash, the time of the crash(including time zone), the identity of the vehicle (e.g., VIN,make/model, license plate number, etc.), the identity of the driverinvolved in the crash (e.g., name, customer number, driver's licensenumber, etc.), and the identity of the mobile device 216 (e.g., IMEI,MAC address, IP address, etc.). For example, the time may be representedby a timestamp in the following format: YYYY-MM-DD HH:MM:SS−ZZZZ. −ZZZZmay stand for time zone offset from UTC (e.g., −0500 is Eastern StandardTime). In some aspects, the mobile device 216 may send the data to thecrash detection server 250, which may store the data in database 252.The mobile device 216 may also send data for a number of seconds beforeand after the time window (e.g., 5 seconds before and 5 seconds after or10 seconds before and 10 seconds after) to the crash detection server250, and the data may be stored in database 252. By providing this datato the crash detection server 250, the server may be able to compare thebefore, during, and after values to confirm the crash. The crashdetection server 250 may also use the stored information to make fastinsurance claim determinations (relative to if the driver reports thecrash days or weeks later), begin estimating vehicle damage costs fasterat the First Notice of Loss (FNOL), and identify the location ofaccidents.

In step 460, the computing device may notify one or more individuals ofthe crash, via email, a telephone call, an on-screen pop-up, or anyother communication medium. For example, the computing device maycontact emergency personnel, such as local fire or police personnel. Themessage to the emergency personnel may include the location of thecrash, the identity of the driver involved in the crash, the licenseplate number of the vehicle, the severity of the crash, and the like.The computing device may similarly send messages to other individuals,such as the driver's emergency contact identified in his or her profilestored in database 252. The computing device may also attempt to contactthe driver or passenger of the vehicle involved in the crash. Forexample, the computing device may attempt to call the mobile device 216or an onboard vehicle communication system in the vehicle 210.Additionally or alternatively, the computing device may provideemergency personnel with the phone number of the mobile device 216,which they may use to contact individuals in the vehicle.

Returning to step 420, the computing device may determine that the timewindow ended (step 420: Y), without the acceleration count exceeding thethreshold number of acceleration events needed to determine that a crashoccurred. In response, the computing device may determine that anon-crash event occurred, such as the mobile device 216 being dropped ora hard braking event. For example, if the mobile device 216 is dropped,the computing device might only detect one or two high magnitude events(compared to three or four for a crash). Accordingly, in step 440, thecomputing device may determine whether the number of high magnitudeacceleration events falls below a mobile device drop threshold, such astwo or three. If so (step 440: Y), the computing device may determine,in step 470, that the mobile device was dropped. The computing devicemay optionally return to step 405 to detect for additional triggerevents and/or crashes. Otherwise, in step 475, the computing device maydetermine that a hard braking event occurred. The computing device mayreturn to step 405 to detect for additional trigger events and/orcrashes.

While the aspects described herein have been discussed with respect tospecific examples including various modes of carrying out aspects of thedisclosure, those skilled in the art will appreciate that there arenumerous variations and permutations of the above described systems andtechniques that fall within the spirit and scope of the invention.

What is claimed is:
 1. A mobile device comprising: an accelerometer;communication circuitry; a processor; and memory storingcomputer-executable instructions that, when executed by the processor ofthe mobile device, cause the processor of the mobile device to: start atime window for measuring acceleration using the accelerometer, whereinthe time window comprises a time duration; during the time duration,receive, from the accelerometer, a plurality of accelerationmeasurements measured by the accelerometer; based on the plurality ofacceleration measurements measured by the accelerometer and receivedduring the time duration, determine a number of acceleration eventsoccurring during the time window; when the number of acceleration eventsoccurring during the time window does not exceed a threshold number ofacceleration events, determine that the mobile device was dropped or avehicle associated with the mobile device was involved in a brakingevent; and send, via the communication circuitry and to a computingdevice, one or more of data indicating that the mobile device wasdropped or data indicating that the vehicle was involved in a brakingevent.
 2. The mobile device of claim 1, wherein determining that themobile device was dropped or the vehicle was involved in a braking eventcomprises: determining, based on a determination that the number ofacceleration events occurring during the time window does not exceed asecond threshold number of acceleration events, that the mobile devicewas dropped, wherein the second threshold number of acceleration eventsis less than the threshold number of acceleration events.
 3. The mobiledevice of claim 1, wherein determining that the mobile device wasdropped or the vehicle was involved in a braking event comprises:determining, based on a determination that the number of accelerationevents occurring during the time window exceeds a second thresholdnumber of acceleration events, that the vehicle was involved in abraking event, wherein the second threshold number of accelerationevents is less than the threshold number of acceleration events.
 4. Themobile device of claim 1, wherein the memory stores computer-executableinstructions that, when executed by the processor of the mobile device,cause the processor of the mobile device to: receive, from theaccelerometer, an acceleration measurement measured by theaccelerometer; determine a magnitude of the acceleration measurementmeasured by the accelerometer; and based on determining that themagnitude of the acceleration measurement measured by the accelerometerexceeds an acceleration magnitude threshold, determine that a triggerevent has occurred, wherein starting the time window is based ondetermining that the trigger event has occurred.
 5. The mobile device ofclaim 1, wherein the memory stores computer-executable instructionsthat, when executed by the processor of the mobile device, cause theprocessor of the mobile device to: determine whether a change in speedof the vehicle exceeds a threshold change in speed; and based ondetermining that the change in speed of the vehicle exceeds thethreshold change in speed, determine that a trigger event has occurred,wherein starting the time window is based on determining that thetrigger event has occurred.
 6. The mobile device of claim 5, furthercomprising a global positioning satellite (GPS) sensor, whereindetermining whether the change in speed of the vehicle exceeds thethreshold change in speed is based on a change in speed measured by theGPS sensor of the mobile device.
 7. The mobile device of claim 1,wherein the memory stores computer-executable instructions that, whenexecuted by the processor of the mobile device, cause the processor ofthe mobile device to: periodically measure, via the accelerometer andwithin the time window for measuring acceleration using theaccelerometer, acceleration, wherein receiving the plurality ofacceleration measurements measured by the accelerometer comprisesreceiving the periodically measured acceleration measured via theaccelerometer.
 8. The mobile device of claim 1, wherein a magnitude ofeach of the acceleration events occurring during the time window exceedsan acceleration magnitude threshold.
 9. The mobile device of claim 1,wherein the mobile device comprises a mobile phone.
 10. A methodcomprising: starting, by a processor of a mobile device, a time windowfor measuring acceleration using an accelerometer, wherein the timewindow comprises a time duration; during the time duration, receiving,by the processor of the mobile device and from the accelerometer, aplurality of acceleration measurements measured by the accelerometer;based on the plurality of acceleration measurements measured by theaccelerometer and received during the time duration, determining, by theprocessor of the mobile device, a number of acceleration eventsoccurring during the time window; when the number of acceleration eventsoccurring during the time window does not exceed a threshold number ofacceleration events, determining that the mobile device was dropped or avehicle associated with the mobile device was involved in a brakingevent; and sending, by the mobile device, via communication circuitryassociated with the mobile device, and to a computing device, one ormore of data indicating that the mobile device was dropped or dataindicating that the vehicle was involved in a braking event.
 11. Themethod of claim 10, wherein determining that the mobile device wasdropped or the vehicle was involved in a braking event comprises:determining, based on a determination that the number of accelerationevents occurring during the time window does not exceed a secondthreshold number of acceleration events, that the mobile device wasdropped, wherein the second threshold number of acceleration events isless than the threshold number of acceleration events.
 12. The method ofclaim 10, wherein determining that the mobile device was dropped or thevehicle was involved in a braking event comprises: determining, based ona determination that the number of acceleration events occurring duringthe time window exceeds a second threshold number of accelerationevents, that the vehicle was involved in a braking event, wherein thesecond threshold number of acceleration events is less than thethreshold number of acceleration events.
 13. The method of claim 10,further comprising: receiving, from the accelerometer, an accelerationmeasurement measured by the accelerometer; determining a magnitude ofthe acceleration measurement measured by the accelerometer; and based ondetermining that the magnitude of the acceleration measurement measuredby the accelerometer exceeds an acceleration magnitude threshold,determining that a trigger event has occurred, wherein starting the timewindow is based on determining that the trigger event has occurred. 14.The method of claim 10, further comprising: determining whether a changein speed of the vehicle exceeds a threshold change in speed; and basedon determining that the change in speed of the vehicle exceeds thethreshold change in speed, determining that a trigger event hasoccurred, wherein starting the time window is based on determining thatthe trigger event has occurred.
 15. The method of claim 14, whereindetermining whether the change in speed of the vehicle exceeds thethreshold change in speed is based on a change in speed measured by aglobal positioning satellite (GPS) sensor of the mobile device.
 16. Themethod of claim 10, further comprising: periodically measuring, via theaccelerometer and within the time window for measuring accelerationusing the accelerometer, acceleration, wherein receiving the pluralityof acceleration measurements measured by the accelerometer comprisesreceiving the periodically measured acceleration measured via theaccelerometer.
 17. The method of claim 10, wherein a magnitude of eachof the acceleration events occurring during the time window exceeds anacceleration magnitude threshold.
 18. The method of claim 10, whereinthe mobile device comprises a mobile phone.
 19. A non-transitorycomputer readable medium storing instructions that, when read by aprocessor of a mobile device, cause the processor of the mobile deviceto: start a time window for measuring acceleration using anaccelerometer, wherein the time window comprises a time duration; duringthe time duration, receive, from the accelerometer, a plurality ofacceleration measurements measured by the accelerometer; based on theplurality of acceleration measurements measured by the accelerometer andreceived during the time duration, determine a number of accelerationevents occurring during the time window; when the number of accelerationevents occurring during the time window does not exceed a thresholdnumber of acceleration events, determine that the mobile device wasdropped or a vehicle associated with the mobile device was involved in abraking event; and send, via communication circuitry associated with themobile device and to a computing device, one or more of data indicatingthat the mobile device was dropped or data indicating that the vehiclewas involved in a braking event.
 20. The non-transitory computerreadable medium of claim 19, wherein determining that the mobile devicewas dropped or the vehicle was involved in a braking event comprises:determining, based on a determination that the number of accelerationevents occurring during the time window does not exceed a secondthreshold number of acceleration events, that the mobile device wasdropped, wherein the second threshold number of acceleration events isless than the threshold number of acceleration events.